Dear Family Member...

Dear family member who keeps using my toothpaste,

Please squeeze from the bottom of the tube. It may seem like a ridiculous request to you, but I would very much appreciate it.
If you cannot find it in your heart to grant me this favour, please just leave my toothpaste alone. I brush my teeth in that bathroom for a reason; nobody else usually does. I don’t want to share my tube of toothpaste with you, anyway.
Let us try to get along, as family members must.

Best Wishes,
Your OCD Daughter/Sister/Aunt